Rails logger format string configuration

Question

How can I configure the rails logger to output its log strings in another format? I would like to get something that is more informative like:

[Log Level] [Time] [Message]

Debug : 01-20-2008 13:11:03.00 : Method Called

This would really help me when I want to tail my development.log for messages that only come from a certain log level, like debug.

Answer 1

The problem with tags is that they clutter your logs to the point where they are unreadable.

I'd recommend something like timber. It automatically augments your logs with context (level, time, session id, etc) without sacrificing readability.

Answer 2

For rails 4 apps, I've put together a simple gem that not only adds support for basic tagging like time stamp and log level, but even adds color to the log messages themselves.

https://github.com/phallguy/shog

Answer 3

Did some digging and found this post in the RubyOnRails Talk google group.

So I modified it a little bit and put it at the end of my environment.rb:

module ActiveSupport
  class BufferedLogger
    def add(severity, message = nil, progname = nil, &block)
      return if @level > severity
      message = (message || (block && block.call) || progname).to_s

      level = {
        0 => "DEBUG",
        1 => "INFO",
        2 => "WARN",
        3 => "ERROR",
        4 => "FATAL"
      }[severity] || "U"

      message = "[%s: %s #%d] %s" % [level,
                                     Time.now.strftime("%m%d %H:%M:%S"),
                                     $$,
                                     message]

      message = "#{message}\n" unless message[-1] == ?\n
      buffer << message
      auto_flush
      message
    end
  end
end

This results in a format string like this:

[DEBUG: 0121 10:35:26 #57078] Rendered layouts/_header (0.00089)

Answer 4

# config/initializers/rack_logger.rb
module Rails
  module Rack
    class Logger < ActiveSupport::LogSubscriber
      # Add UserAgent
      def started_request_message(request)
         'Started %s "%s" for %s at %s by %s' % [
          request.request_method,
          request.filtered_path,
          request.ip,
          Time.now.to_default_s,
          request.env['HTTP_USER_AGENT'] ]
      end
    end
  end
end

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